Liquid crystal display device

ABSTRACT

Disclosed is an active matrix liquid crystal display device including substrates and a liquid crystal layer. The substrate includes: scan signal wiring lines; common signal wiring lines; video signal wiring lines intersecting these wiring lines; and pixels surrounded with the scan signal wiring lines and the video signal wiring lines. Each of pixels includes: a thin film transistor; source electrodes in a layer with the video signal wiring lines; pixel electrodes connected to the source electrodes; and common electrodes connected to the common signal wiring lines. The source electrodes include first parts overlapping the scan signal wiring lines and second parts connecting with the pixel electrodes, which are positioned around central parts between the video signal wiring lines. Molecular axes in the liquid crystal layer rotate under an electric field applied between the pixel electrodes and the common electrodes.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromJapanese Patent Application Nos. 2006-219322 filed on Aug. 11, 2006 and2007-060758 filed on Mar. 9, 2007, the disclosure of which isincorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a liquid crystal display (LCD) device,and particularly relates to an LCD device of an active matrix type in anIn-Plane Switching (IPS) mode of a high aperture ratio and highcontrast.

2. Background Art

A display of a twisted nematic (TN) system with high contrast is widelyused. However, since molecular axes of liquid crystal (LC) moleculesrise by a vertical electric field, a display device of the TN systemincludes a significant viewing angle dependency. In recent years, asdemand for a large monitor of a TV is increasing, an IPS mode becomeswidespread. In a display device of the IPS mode, molecular axes of LCmolecules rotate by a horizontal electric field in a plane parallel to asubstrate to perform display. Since the IPS mode does not includeviewing angle dependency over a rising angle of the molecular axes,viewing angle characteristics thereof is substantially more advantageousthan that of the TN system.

In a display device of the IPS mode, pixel electrodes and commonelectrodes are arranged in a shape like a comb teeth, and a horizontalelectric field is applied between the pixel electrodes and the commonelectrodes. For this reason, a ratio of an electrode area to displayareas is large. That is, the display device of the IPS mode includes alow aperture ratio. Since the display device of the IPS mode is drivenby a horizontal electric field, LC molecules in display areas tend to beaffected by an electric field leaked from video signal wiring lines anda vertical cross talk easily occurs.

For example, a solution for such problem is disclosed in Japanese PatentApplication Laid-Open No. 2002-323706 (patent document 1). FIG. 35Ashows one pixel plan view and FIG. 35B shows a cross sectional viewalong lines I-I, II-II and III-III. A plurality of scan signal wiringlines 3501, which are first metal layers, and two common signal wiringlines 3502 in parallel thereto are formed on a substrate. A firstinsulating film 3503 is formed on the plurality of scan signal wiringlines and the plurality of common signal wiring lines. A plurality ofvideo signal wiring lines 3504, which are second metal layers, a thinfilm transistor (TFT) 3505 and source electrodes 3506 are formed on thefirst insulating film. The source electrodes 3506 are disposed at bothsides of a plurality of pixels, and are connected to pixel auxiliarywiring lines 3506B that are located in the same layer as the sourceelectrodes. The respective source electrodes 3506 form a storagecapacitance in areas overlapped the plurality of common signal wiringlines 3502. The source electrodes 3506 and the plurality of commonsignal wiring lines 3502 are patterned like a saw shape.

In edges in display areas, the saw-like pattern portions suppress anelectric field which causes a reverse-rotation of LC molecules. A secondinsulating film 3507 is formed on the plurality of video signal wiringlines 3504, the TFT 3505 and the source electrodes 3506. A thirdinsulating film 3508 that is a transparent insulating film is formed onthe second insulating film 3507. Pixel electrodes 3509 and commonelectrodes 3510 which are transparent electrodes are formed on the thirdinsulating film 3508. The plurality of video signal wiring lines 3504are completely covered by the common electrodes 3510 in a wiring linewidth direction via the second insulating film 3507 and the thirdinsulating film 3508. The pixel electrodes 3509 and the commonelectrodes 3510 are electrically connected to the source electrodes 3506and the plurality of common signal wiring lines 3502 respectively viacontact holes 3511 and 3512.

The pixel electrodes 3509 and the common electrodes 3510 which arearranged in a shape of comb teeth are transparent electrodes. Thus,areas on the electrode contribute to transmittance. According to asimulation, contribution to the transmittance of the transparentelectrodes increases an effective aperture ratio by about 8%. Sinceareas on the plurality of video signal wiring lines are completelycovered by the common electrodes in the wiring line width direction, itis possible to extend an opening to areas near the plurality of videosignal wiring lines. Thus, reverse-rotation of liquid crystal moleculesis prevented in edges in the display areas, and efficiency for lightutilization rises to a maximum extent.

Leaked electric fields from the plurality of video signal wiring linesare shielded by the common electrodes. Accordingly, vertical cross talkdecreases. Further, although load capacity occurs between the pluralityof video signal wiring lines and the common electrodes, the loadcapacity does not influence drive of the display device because of aninsulating film having low dielectric constant.

A solution to the above problem is also disclosed in Japanese PatentApplication Laid-Open No. 2003-207803 (patent document 2). FIG. 37Ashows a plan view of one pixel and FIG. 37B shows a cross sectional viewalong lines I-I, II-II and III-III. A plurality of scan signal wiringlines 3701 that are first metal layers, and two common signal wiringlines 3702 in parallel thereto are formed. A first insulating film 3703is formed on the plurality of scan signal wiring lines 3701 and theplurality of common signal wiring lines 3702. A plurality of videosignal wiring lines 3704 that are second metal layers, a TFT 3705 andsource electrodes 3706 are formed on the first insulating film. Althoughsource electrodes 3706 are provided at both sides of a plurality ofpixels in FIG. 37A, the source electrodes are not connected to eachother in the same layer. The respective source electrodes 3706 areconnected electrically via contact holes 3711, 3713 and pixel electrodes3709. The respective source electrodes 3706 form a storage capacitancein the areas overlapped the plurality of common signal wiring lines3702.

The source electrodes 3706 and the plurality of common signal wiringlines 3702 are patterned like a saw shape. In edges in display areas,the saw-like pattern suppresses an electric field which causesreverse-rotation of LC molecules. A second insulating film 3707 isformed on the plurality of video signal wiring lines 3704, the TFT 3705and the source electrodes 3706. A third clear insulating film 3708 isformed on the second insulating film 3707. The pixel electrodes 3709 andcommon electrodes 3710 which are transparent electrodes are formed onthe third insulating film 3708. The plurality of video signal wiringlines 3704 are completely covered by the common electrodes 3710 in awiring line width direction via the second insulating film 3707 and thethird insulating film 3708. The pixel electrode 3709 and commonelectrodes 3710 are electrically connected to the source electrodes 3706and the plurality of common signal wiring lines 3702 respectively viacontact holes 3711, 3712 and 3713.

In recent years, a liquid crystal display (LCD) device with highdefinition is required. In the patent document 1, high-definition LCD isnot realized. The second metal layer is illustrated on FIG. 36A. Whenthe plurality of video signal wiring lines 3604 and the pixel auxiliarywiring lines 3606B become close in the same layer, a foreign particle orthe like tend to cause short-circuiting therebetween. FIG. 36B shows anexample in which the two wiring lines short-circuit. The plurality ofvideo signal wiring lines 3604 and the pixel auxiliary wiring lines3606B are connected through a leak pass 3606C. Electric potential of thepixel electrode is influenced by change of electric potential of videosignal wiring lines 3604 in this state. A leaked pass looks like abright point on a dark screen and looks like a dark point on a lightscreen. Hereinafter, such a point defect which performs like above iscalled “a leak bright point”. A demand to the image quality is increasedin recent years, and in particular, a display device without the leakbright point is strongly required.

In the patent document 2, a contact hole 3713 is disposed and two sourceelectrodes 3706 are connected via a transparent pixel electrode 3709. Byeliminating pixel auxiliary wiring lines in the same layer,short-circuiting to a plurality of video signal wiring lines in the samelayer is decreased. However, even in such configurations, the sourceelectrodes and a plurality of video signal wiring lines highly tend toshort-circuit. FIG. 38A shows only a second metal layer. Because astorage capacitance is formed between the source electrodes 3806 and theplurality of common signal wiring lines 3802, the source electrodes 3806must be arranged so as to be more adjacent to the plurality of videosignal wiring lines 3804 than the pixel auxiliary wiring lines. FIG. 38Bshows that the plurality of video signal wiring lines 3804 and thesource electrodes 3806, which are formed in the same layer, makeshort-circuiting through a leaked pass 3806C. In such configuration,potential of the pixel electrode is influenced by change in electricpotential of the plurality of video signal wiring lines 3804, and theleak bright point occurs as stated in the patent document 1. By removingthe pixel auxiliary wiring lines, short-circuiting in the same layer isreduced to some extent compared with the patent document 1. However,substantial reduction is not realized.

The display devices in the related art display form a storagecapacitance by overlapping between the plurality of common signal wiringlines and the source electrodes. In the display device, short-circuitingbetween the plurality of video signal wiring lines and the sourceelectrodes is still likely. Thus, improvement of substantial yield isdifficult in the related art.

SUMMARY

The main object of the present application is to suppressshort-circuiting between a plurality of video signal wiring lines andsource electrodes to provide an active matrix LCD device of a lateralelectric field type which can realize high yield.

According to an aspect of the present invention, an active matrix liquidcrystal display device includes: a first substrate, a second substratefacing the first substrate, and a liquid crystal layer sandwiched by thefirst substrate and the second substrate. The first substrate includes:a plurality of scan signal wiring lines; a plurality of common signalwiring lines disposed along the plurality of scan signal wiring lines; aplurality of video signal wiring lines intersecting the plurality ofscan signal wiring lines and the plurality of common signal wiringlines; and a plurality of pixels. The plurality of pixels are disposedin a first region surrounded with the plurality of scan signal wiringlines and the plurality of video signal wiring lines. The pixelincludes: a thin film transistor; source electrodes of the thin filmtransistor formed in a layer in which the plurality of video signalwiring lines are disposed; pixel electrodes connected to the sourceelectrodes; and common electrodes connected to the plurality of commonsignal wiring lines. The source electrodes include a first partoverlapping the plurality of scan signal wiring lines and a second partconnecting with the pixel electrode. The second part is positionedaround a central part between the video signal wiring lines in a side ofthe plurality of pixels. Molecular axes of a liquid crystal molecule inthe liquid crystal layer rotate in a first direction in a planeapproximately parallel to the first substrate under an electric field,which is approximately parallel to the first substrate and is appliedbetween the pixel electrode and the common electrodes.

According to an active matrix LCD device of a lateral electric fieldtype of the present invention, following advantageous effects areobtained.

Firstly since short-circuit between source electrodes and a plurality ofvideo signal wiring lines highly decreases, high yield in ahigh-definition product be comes possible. The reasons are as follows.The source electrodes and the pixel auxiliary wiring lines both locatedin a side of a plurality of pixels are formed in a layer which isdifferent from a layer where the plurality of video signal wiring linesare located. The area of the source electrodes which are located inother side of the pixel and in the same layer as the plurality of videosignal wiring lines is reduced. The distances between the edges ofpatterns (interval of facing sides of the patterns) in the same layerbecome large.

Secondarily reverse-rotation of LC molecules is also prevented in theabove-mentioned structure. A direction of molecular axis rotation basedon a fringe electric field in an LC layer and a desired direction ofmolecular axis rotation therein are identical in areas where pixelelectrodes in a top layer and a plurality of common signal wiring linesin a bottom layer intersect. A strong electric field which rotates themolecular axes in forward rotational direction occurs in the areas.Thus, even if the source electrodes are removed, reverse-rotation of LCmolecules is prevented by the new reverse-rotation preventing structure.

Other exemplary features and advantages of the present invention isapparent from the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary features and advantages of the present invention becomeapparent from the following detailed description when taken with theaccompanying drawings in which:

FIG. 1A is a plan view showing the composition of one pixel of an LCDdevice according to a first exemplary embodiment;

FIG. 1B is a cross sectional view showing a specified partialconfiguration in FIG. 1A of the LCD device according to the firstexemplary embodiment;

FIG. 2A is a plan view showing a configuration of a second metal layerof an LCD device according to a second exemplary embodiment;

FIG. 2B is a plan view showing the configuration of the second metallayer of a conventional LCD device;

FIG. 3A is a plan view showing a configuration of one pixel of an LCDdevice according to third and fourth exemplary embodiments;

FIG. 3B is a cross sectional view showing a specified partialconfiguration in FIG. 3A of the LCD device according to the third andfourth exemplary embodiments;

FIG. 4 is a plan view showing a configuration of one pixel of an LCDdevice according to a fifth exemplary embodiment;

FIG. 5 is a plan view showing a pixel of configuration of an LCD deviceaccording to a sixth exemplary embodiment;

FIGS. 6A and 6B are plan views showing a pixel of configuration of anLCD device according to a seventh exemplary embodiment;

FIGS. 7A and 7B are diagram illustrating a structure that prevents afirst reverse-rotation preventing structure in an LCD device accordingto the seventh exemplary embodiment;

FIG. 8 is a plan view showing a pixel of configuration of an LCD deviceaccording to eighth and ninth exemplary embodiments;

FIG. 9 is a plan view showing a pixel of configuration of an LCD deviceaccording to a tenth exemplary embodiment;

FIG. 10 is a plan view showing a pixel of configuration of an LCD deviceaccording to an eleventh exemplary embodiment;

FIG. 11 is a plan view showing a pixel of configuration of an LCD deviceaccording to a twelfth exemplary embodiment;

FIG. 12 is a plan view showing a pixel of configuration of an LCD deviceaccording to thirteenth to fourteenth exemplary embodiments;

FIG. 13 is a plan view showing a pixel of configuration of an LCD deviceaccording to a fifteenth exemplary embodiment;

FIG. 14 is a plan view showing a pixel of configuration of an LCD deviceaccording to a sixteenth exemplary embodiment;

FIG. 15 is a plan view showing a pixel of configuration of an LCD deviceaccording to a seventeenth exemplary embodiment;

FIG. 16 is a diagram illustrating a first reverse-rotation preventingstructure in the LCD device according to eighteenth to twentiethexemplary embodiments;

FIG. 17 is a plan view showing a pixel of configuration of an LCD deviceaccording to twenty-first to twenty-second exemplary embodiments;

FIG. 18 is a diagram illustrating a second reverse-rotation preventingstructure in the LCD device according to a twenty-first exemplaryembodiment;

FIG. 19 is a plan view showing a pixel of configuration of an LCD deviceaccording to a twenty-third exemplary embodiment;

FIG. 20 is a plan view showing a pixel of configuration of an LCD deviceaccording to a twenty-fourth exemplary embodiment;

FIG. 21 is a plan view showing a pixel of configuration of an LCD deviceaccording to a twenty-fifth exemplary embodiment;

FIG. 22 is a plan view showing a pixel of configuration of an LCD deviceaccording to twenty-sixth to twenty-seventh exemplary embodiments;

FIG. 23 is a diagram illustrating a second reverse-rotation preventingstructure in the LCD device according to the twenty-sixth exemplaryembodiment;

FIG. 24 is, a plan view showing a pixel of configuration of an LCDdevice according to a twenty-eighth exemplary embodiment;

FIG. 25 is a plan view showing a pixel of configuration of an LCD deviceaccording to a twenty-ninth exemplary embodiment;

FIG. 26 is a plan view showing a pixel of configuration of an LCD deviceaccording to a thirtieth exemplary embodiment;

FIG. 27 is a plan view showing a pixel of configuration of an LCD deviceaccording to thirty-first to thirty-second exemplary embodiments;

FIG. 28 is a plan view showing a pixel of configuration of an LCD deviceaccording to a thirty-third exemplary embodiment;

FIG. 29 is a plan view showing a pixel of configuration of an LCD deviceaccording to a thirty-fourth exemplary embodiment;

FIG. 30 is a plan view showing a pixel of configuration of an LCD deviceaccording to a thirty-fifth exemplary embodiment;

FIG. 31 is a plan view showing a pixel of configuration of an LCD deviceaccording to thirty-sixth to thirty-seventh exemplary embodiment;

FIG. 32 is a plan view showing a pixel of configuration of an LCD deviceaccording to a thirty-eighth exemplary embodiment;

FIG. 33 is a plan view showing a pixel of configuration of an LCD deviceaccording to a thirty-ninth exemplary embodiment;

FIG. 34 is a plan view in the neighborhood of a second reverse-rotationpreventing structure of an LCD device according to a fortieth exemplaryembodiment;

FIG. 35A is a plan view showing a pixel of configuration of an LCDdevice on a related art;

FIG. 35B is a cross sectional view which shows a specified partialconfiguration in FIG. 35A of an LCD device on the related art;

FIG. 36A is a plan view showing a configuration of a second metal layerof an LCD device on the related art;

FIG. 36B is a figure illustrating an example in which the layer shortcircuit of a plurality of video signal wiring lines and pixel auxiliarywiring lines has occurred in the second metal layer of an LCD device onthe related art;

FIG. 37A is a plan view showing a pixel of configuration of an LCDdevice on another related art;

FIG. 37B is a cross sectional view showing a specified partialconfiguration in FIG. 37A of an LCD device on the related art;

FIG. 38A is a plan view showing a configuration of a second metal layerof an LCD device on the related art; and

FIG. 38B is a diagram illustrating an example of short-circuit between aplurality of video signal wiring lines and source electrodes which haveoccurred at the same layer in the second metal layer of an LCD device ofthe related art.

EXEMPLARY EMBODIMENT

Exemplary embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

In an exemplary embodiment, an active matrix liquid crystal displaydevice of an IPS mode includes source electrodes of a TFT. The sourceelectrodes of the TFT are formed in a first part that connects with aTFT, a second part that connects with pixel electrodes and a third partthat connects the first part and the second part. The second part isarranged in the almost center part between video signal wiring lines. Apositional relationship between the source electrodes and video signalwiring lines is defined by a total of a value which is obtained when awidth of each area of the source electrodes facing at least a part ofthe plurality of video signal wiring lines is divided by distancesbetween the areas and the plurality of video signal wiring lines. Bycontrolling the total value, a short circuit of the source electrodesand the plurality of video signal wiring lines is suppressed. Thus, ahigh-definition display device with high yield can be produced. Astorage capacitance is formed in a part where pixel electrodes overlap aplurality of common signal wiring lines in a normal direction of asubstrate. When at least a part of a second insulating film just belowthe pixel electrode is removed to form a concave portion, a storagecapacitance is formed. In areas where a top layer pixel electrodeintersect with a bottom layer common signal wiring lines, molecular axesof LC molecules in an LC layer rotate in a desired rotational directionby a fringe electric field. In the areas, a strong electric field forforward rotation occurs. Even when source electrodes are reduced in suchconfiguration, reverse-rotation of LC molecules is prevented.Hereinafter, an exemplary embodiment is described in detail withreference to drawings.

Exemplary Embodiment 1

A first exemplary embodiment is described by referring to FIGS. 1A and1B. FIG. 1A is a plan view showing a pixel configuration of an LCDdevice. FIG. 1B is a cross sectional view along an IV-IV line and a V-Vline in FIG. 1A.

As shown in FIGS. 1A and 1B, a TFT substrate of the LCD device includesa plurality of scan signal wiring lines 101 that are first metal layersand two common signal wiring lines 102 therealong. A first insulatingfilm 103 is formed on the plurality of scan signal wiring lines 101 andcommon signal wiring lines 102. A plurality of video signal wiring lines104 that are second metal layers, a TFT 105 and source electrodes 106are formed on the first insulating film 103. Here, the source electrodes106 include a first portion (1) connected with the TFT 105 and a secondportion (2) connected with pixel electrodes 109. The second portion (2)is arranged in the approximate center of the video signal wiring lines104 on both sides of a plurality of pixels. The source electrodes 106include the first and the second part, but a shape thereof is notlimited to a configuration in the drawing.

A second insulating film 107 is formed on the plurality of video signalwiring lines 104, the TFT 105 and the source electrodes 106. A thirdtransparent insulating film 108 is formed on the second insulating film107. The pixel electrode 109 and the common electrodes 110 which aretransparent electrodes are formed on the third insulating film 108. Theplurality of video signal wiring lines 104 are completely covered by thecommon electrodes 110 in a direction of the wiring line width via thesecond insulating film 107 and the third insulating film 108. The sourceelectrodes 106 located in a layer which the plurality of video signalwiring lines 104 are arranged are formed only under the pixel as shownin FIG. 1A. In the upper side of the pixel, a width of the pixelelectrode 109 in the top layer increases. In areas where the pluralityof common signal wiring lines 102 overlap the pixel electrode 109, astorage capacitance is formed.

The pixel electrode 109 and the common electrodes 110 are electricallyconnected to the second portion 2 of the source electrodes 106, and theplurality of common signal wiring lines 102 via contact holes 111 and112, respectively.

The first exemplary embodiment removes the source electrodes which areformed in an upper side of the pixel and formed in the layer which theplurality of video signal wiring lines are arranged compared with therelated art. Accordingly, a contact hole for electrically connecting thepixel electrode and the source electrodes which are formed in a lowerlayer of the plurality of pixels is not needed. A short circuitdecreases substantially.

The second portion of the source electrodes and the plurality of videosignal wiring lines exist in the same layer. When the second portion ofthe source electrodes is arranged in the approximate center between thevideo signal wiring lines located on both sides of the pixel, a shortcircuit between the second portion thereof and the signal wiring linescan be reduced to the minimum. As a result, an LCD device with highyield can be realized.

More than half of a storage capacitance is formed at a part where thepixel electrode overlaps the plurality of common signal wiring lines.Thereby, an enough storage capacitance is also formed even when areas ofthe source electrodes are reduced. Thus the excellent image quality isobtained.

Exemplary Embodiment 2

Next, a second exemplary embodiment is described by referring to FIGS.2A and 2B. FIG. 2A is a plan view showing a structure of a second metallayer of an LCD device. FIG. 2B is a plan view showing a structure of asecond metal layer of an LCD device according to a related art.

The second exemplary embodiment defines areas of source electrodes, eachwidth of areas of the source electrodes, and distances between the areasand opposing video signal wiring lines.

As shown in FIG. 2A, regarding each of areas of source electrodes 206,edges of which face at least parts of a plurality of video signal wiringlines 204, Wi represents a width of the area and Li represents distancesof the areas and the plurality of video signal wiring lines 204. Asummation value (ΣWi/Li) of Wi/Li in a pixel serves as a good parameterwhich shows frequency of a short circuit in the same layer. The smallvalue of ΣWi/Li means desirable condition. When the value of ΣWi/Li iswithin two times of the value (W0/L0) which is obtained when a channelwidth W0 of a TFT is divided by a channel distance L0 thereof, thefrequency of the short circuit between the source electrodes and theplurality of video signal wiring lines becomes enough small. Under suchcondition, high yield is obtained.

In a display device of a related art, three or four leak bright pointsin a panel detected. In the exemplary embodiment, no leak bright pointis detected.

In another viewpoint, it is desirable for the area of source electrodes206 to be small. When the total area of the source electrodes is 4 timesor less than 4 times of sum of both areas of a first part and a secondpart in the source electrodes, the frequency of the short circuitbetween the source electrodes and the plurality of video signal wiringlines becomes enough small. Thus, display device with high yield isobtained. When the total area thereof is 4 times or less than 4 times ofthe sum of both areas of the first part and the second part, one or zeroleak bright point occurs. When the total area thereof is 3 times or lessthan 3 times of the sum of both areas of the first part and the secondpart, no leak bright point occurs.

Next, the second exemplary embodiment is described in detail. In theconfiguration of the exemplary embodiment as shown in FIG. 2A, sinceareas of the source electrodes 206 are small, parameter ΣWi/Li, i.e.,the value of (W1/L1+ . . . +W5/L5), is also small. The total area of thesource electrodes is about 2.5 times of the sum of both areas of thefirst part and the second part. The value of parameter ΣWi/Li is about2.5 and is nearly equal to the value of W0/L0. Under the condition, aleak bright point does not occur.

On the other hand, in a configuration of the related art as shown inFIG. 2B, the area of source electrodes 206 is large. Areas where Wi islarge and areas where Li is small exist a lot. The parameter ΣWi/Li,i.e., the value of (W1/L1+ . . . +W8/L8), is large. The total area ofthe source electrodes is about 9 times of the sum of both areas of thefirst part and the second part. The parameter ΣWi/Li is about 20 and isabout 8 times of the value of W0/L0. Under such condition, four or threeleak bright points occur.

Thus, according to the second exemplary embodiment, a pixel structurewhich substantially reduces a short circuit is given.

Exemplary Embodiment 3

Next, a third exemplary embodiment is described by referring to FIGS. 3Aand 3B. FIG. 3A is a plan view showing one pixel configuration of an LCDdevice and FIG. 3B is a sectional view along a Σ-Σ line and a Σ-Σ linein FIG. 3A. Unlike the first exemplary embodiment, in a region where astorage capacitance is formed, a part of a third insulating layer whichis located just below pixel electrodes is removed by predeterminedthickness.

The third exemplary embodiment is described in detail. A storagecapacitance is formed between a plurality of common signal wiring linesin a bottom layer and pixel electrodes in a top layer in the firstexemplary embodiment. However, since three insulating layers arearranged between the plurality of common signal wiring lines and thepixel electrode in the first exemplary embodiment, thickness of theinsulating layers for the storage capacitance is large. Therefore, thecapacity of a storage capacitance is small. According to the exemplaryembodiment, in the region where the storage capacitance is formed, thethird insulating layer 308 which is located just below pixel electrodes309 is removed to form a concave portion 314. Since the thickness of theinsulating layer in capacitance forming areas becomes thin, a storagecapacitance with a larger capacity is formed.

Further, a silicon nitride film is formed by CVD (chemical vapordeposition) method as a first insulating film 303 and the secondinsulating film 307, for example. After that, a photosensitive organicfilm made of an acrylic resin is applied as the third insulating film.Next, the concave portion 314 is formed by selectively removing thethird insulating layer 308 by exposure and development. An acrylic resinhas a low dielectric constant. Even if common electrodes are formed on aplurality of video signal wiring lines 304 via the insulating layers, acapacitance value of the storage capacitance between the plurality ofvideo signal wiring lines and common electrodes is small. The storagecapacitance does not influence driving of a plurality of pixels.

The third insulating film 308 is formed by CVD method, and the concaveportion 314 may be formed by an etching. The third insulating film 308which is located just below the pixel electrode 309 may be removedcompletely. The third insulating film 308 may be left thin.

An insulating film arranged on the plurality of video signal wiringlines 304 may include only the second insulating film 307 formed by onelayer, and in storage capacitance forming areas, a part of the secondinsulating film may be removed.

In a case that an insulating layer arranged on the plurality of videosignal wiring lines 304 includes three or more layers, one or morelayers of the laminated insulating layers may be removed in the storagecapacitance forming areas.

Thus, according to the third exemplary embodiment, frequency of a shortcircuit can be substantially decreased while forming a storagecapacitance.

Exemplary Embodiment 4

Next, a fourth exemplary embodiment is described by referring to FIGS.3A and 3B. A distance from edges of the concave portion to display areasis defined in the exemplary embodiment. The concave portion is formed byremoving the third insulating layer which is located just below thepixel electrode. The display areas are regions between pairs of commonsignal wiring lines 302.

The fourth exemplary embodiment is described in detail. When edges ofthe concave portion 314 formed by removing the third insulating film 308are close to display areas, light leak due to a step occurs. Such lightleak causes increase of black-level luminance. The distance from theedges of the concave portion 314 formed by removing the third insulatingfilm 308 to the display areas is defined in the exemplary embodiment.Light leakage may be well suppressed, when the distance becomes large.If the distance is not less than 2□m, the light leakage due to the stepis intercepted with common signal wiring lines 302, and black-levelluminance does not increase.

Thus, according to the fourth exemplary embodiment, while frequency ofthe short circuit decreases substantially, a storage capacitanceequivalent to that of the related art is formed. Because a black-levelluminance does not increase, a contrast of a display screen improves.

Exemplary Embodiment 5

Next, a fifth exemplary embodiment is described by referring to FIG. 4.Two common signal wiring lines arranged in an upper part and a lowerpart of a pixel which respectively correspond to a first storagecapacity forming section and a second storage capacity forming sectionare electrically connected by a connecting part arranged along aplurality of video signal wiring lines.

Since the two common signal wiring lines 402 of an upper part and alower part of the pixel are electrically connected by a connection part402B, delay of a common signal is decreased and the distribution ofluminance or a flicker level within a surface becomes uniform. Theconfiguration contributes to a display with high definition. Therefore,when an device becomes large and high definition is highly required, theconfiguration becomes effective. In the exemplary embodiment, theconnection part 402B is arranged along with a side of a plurality ofvideo signal wiring lines, the leaked electric field from the pluralityof video signal wiring lines to display areas is suppressed strongly,and vertical cross talk is suppressed.

Thus, according to the fifth exemplary embodiment, because frequency ofthe short circuit decreases substantially and delay of the common signalis decreased, improvement of image quality as well as higher yield areobtained.

Exemplary Embodiment 6

Next, a sixth exemplary embodiment is described by referring to FIG. 5.Upper common signal wiring lines which are in a second storagecapacitance forming section is not connected to other line or otherelectrode, in a transverse direction, in areas where a plurality ofvideo signal wiring lines intersect therewith.

The upper common signal wiring lines electrically connect with the lowercommon signal wiring lines via a connection part 502B. A crossingcapacity between the plurality of video signal wiring lines and theplurality of common signal wiring lines become approximately half.

Exemplary Embodiment 7

Next, a seventh exemplary embodiment is described by referring to FIGS.6A and 7B. FIG. 6A is a plan view showing a configuration of one pixelof an LCD device according to the exemplary embodiment. FIG. 6B is aplan view showing one pixel configuration which is not provided with areverse-rotation preventing structure. FIG. 7A shows an operation of LCmolecules in a configuration provided with a reverse-rotation preventingstructure of the exemplary embodiment. FIG. 7B shows an operation of LCmolecules in a configuration which is not provided with thereverse-rotation preventing structure.

In a display device of the related art as shown in FIGS. 35A and 37A,both of a plurality of common signal wiring lines and source electrodesare patterned like a saw shape and laminated. Such configurationsuppresses an electric field which induces reverse-rotation of LCmolecules. Reverse-rotation is described below briefly. When an electricfield is not applied to LC molecules, the LC molecules are orientedhomogeneously in a rubbing direction as shown in the drawings. Whenelectric potential difference is given between pixel electrodes andcommon electrodes, an electric field is applied in a transversedirection in FIG. 35A. In such situation; based on a relation between anelectric field and an initial oriented direction of LC molecules, the LCmolecules deform so as to correspond to a direction of the electricfield. In an example as shown in the drawing, such movement is aclockwise rotation. The rotation of the direction is defined as aforward rotation. A rotation of LC molecules in a rotational directionopposite to the forward rotation is defined as a reverse-rotation. InFIG. 35A, edges of pixel electrodes and common electrodes are formedinto a saw shape. Thereby, in an electrode edge portion, an electricfield is formed in a direction which LC molecules perform the forwardrotation from an initial alignment of LC molecules. Accordingly, thegood oriented state of LC molecules is maintained in an electrode edgeportion. In contrast, in FIG. 1A shown, because areas of sourceelectrodes are small, the same structure as FIG. 35A is not formed. Forexample, in FIG. 1A, an electric field is formed in a direction from adiagonal left to a diagonally right in an upper left side of pixelelectrodes. LC molecules rotate counterclockwise at the areas. A domainin which LC molecules reverse-rotate is formed in the areas, anddisinclination occurs. The disinclination reduces a contrast and whiteluminance. Thus, areas where an electric field which induces thereverse-rotation occurs are defined as a part which is not in accordwith a desired rotational direction of LC molecular axes in a LC layer.On the other hand, in FIG. 1A, in an upper right side of the pixelelectrode, a direction of an electric field is from a diagonal right toa diagonal below. A clockwise rotation is induced in LC molecules in thepart. The part is defined as the part which is in accord with a desiredrotational direction of LC molecular axes of a liquid crystal layer. Inthe exemplary embodiment, a measure which prevents reverse-rotation istaken also in the configuration of the first exemplary embodiment inwhich reduces areas of source electrodes.

In a part (i.e. a part enclosed with the dashed line of the drawing)where a plurality of common signal wiring lines 602 of a bottom layerintersect with pixel electrodes 609 of a top layer as specifically shownin FIG. 6A, the pixel electrode 609 inclines in a direction differentfrom a direction thereof in display areas which are regions between apair of common signal wiring lines 602. In a region on the plurality ofcommon signal wiring lines 602, a reverse-rotation preventing structure615A is formed such that a rotation of LC molecular axes in a LC layeraccording to a fringe electric field generated near edges of the pixelelectrode 609 becomes a forward rotation. According to a rubbingdirection, a inclining direction of the reverse-rotation preventingstructure 615A becomes reverse with each other on both sides of aplurality of pixels in FIG. 6A (i.e. left and right sides in FIG. 6A).

Such a reverse-rotation preventing structure is described by referringto FIGS. 7A and 7B. In FIG. 7B, areas where an electric field whichmakes a reverse rotation of LC molecules occurs are located at edges ofdisplay areas. On the other hand, in FIG. 7A, a reverse rotationpreventing structure 715B is arranged in areas where an electric fieldfor reverse rotation of LC molecules occurs. The reverse rotationpreventing structure 715B includes a configuration in which edges of aplurality of common signal wiring lines 702 intersect with parts ofpixel electrodes which incline in a direction different from a directionthereof in display areas. In a region on the plurality of common signalwiring lines 702, a fringe electric field for a forward rotation occurs.And an influence of a reverse-rotating electric field is inhibited.Thereby, in whole display areas, LC molecules rotate in a forwarddirection. Hereafter, the reverse-rotation preventing structure shown inFIG. 7A is called a first reverse-rotation prevention structure.

Thus, according to the seventh exemplary embodiment, frequency of ashort circuit decreases substantially, reverse-rotation of LC moleculesis prevented in whole display areas, and efficiency for lightutilization increases.

Exemplary Embodiment 8

Next, an eighth exemplary embodiment is described by referring to FIG.8. FIG. 8 is a plan view showing a configuration of a plurality ofpixels of an LCD device. In the exemplary embodiment, a third insulatingfilm just below pixel electrodes is removed in areas in which a storagecapacitance is formed.

Specifically, the storage capacitance is formed between a plurality ofcommon signal wiring lines in a bottom layer and pixel electrodes in atop layer. In the configuration, because three insulating films aredisposed between the plurality of common signal wiring lines and thepixel electrode, film thickness is thick and accordingly, a storagecapacitance is small. In the exemplary embodiment, a concave portion 814is formed by removing a third insulating film just below the pixelelectrode 809 in areas in which a storage capacitance is formed. As aresult, two insulating layers are arranged in storage capacitanceforming areas. Thus, a storage capacitance with larger capacity isformed in the areas.

A silicon nitride film is formed by a chemical vapor deposition (CVD)method as a first and a second insulating film, for example. Aphotosensitive organic film of an acrylic resin is applied as a thirdinsulating film. And a concave portion 814 is formed by selectivelyremoving the third insulating layer by exposure and development. Thethird insulating film may be formed by the CVD method, and the concaveportion 314 may be formed by an etching. The third insulating film justbelow the pixel electrode 809 may be completely removed or may be leftthin.

According to the eighth exemplary embodiment, while frequency of a shortcircuit decreases substantially and reverse-rotation of LC molecules isprevented in whole display areas and a larger storage capacitance can beformed.

Exemplary Embodiment 9

Next, a ninth exemplary embodiment is described by referring to FIG. 8.Further, although the configuration of a device is same as the eighthexemplary embodiment, a distance from edges of a concave portion whichis formed by removing a third insulating film just below pixelelectrodes to display areas is defined in the exemplary embodiment.

When edges of the concave portion 814 formed by removing a thirdinsulating film are close to display areas, light leak due to a stepoccurs. The light leak causes increase of black-level luminance. In theexemplary embodiment, the distance from the edges of the concave portion814 formed by removing the third insulating film to the display areas isdefined. Light leakage is effectively suppressed, when the distance islarge. If distance of not less than 2□m is kept, the light leakage dueto the step is intercepted with common signal wiring lines 802.Accordingly, black-level luminance does not increase.

According to the exemplary embodiment, frequency of a short circuitdecreases substantially, and reverse-rotation of LC molecules isprevented in whole display areas. Since a sufficient storage capacitanceis formed and a black-level luminance does not increase, a contrast of ascreen of a display device improves.

Exemplary Embodiment 10

Next, a tenth exemplary embodiment is described by referring to FIG. 9.Two common signal wiring lines arranged in an upper part and a lowerpart of a pixel which are in a first storage capacity forming sectionand a second storage capacity forming section are electrically connectedto each other via a connection part arranged along a plurality of videosignal wiring lines.

When the two common signal wiring lines 902 of upper side and a lowerside of the pixel are connected via the connection part 902B, delay of acommon signal is decreased and the in-plane distribution of luminance ora flicker level becomes uniform. The configuration contributes to highdefinition of a display. The configuration is so effective for highdefinition of a display when a device is large and is high definition isrequired. In the exemplary embodiment, when the connection part 902B isarranged along the side of the plurality of video signal wiring lines, aleaked electric field from the plurality of video signal wiring lines todisplay areas is suppressed strongly, and vertical cross talk issuppressed.

According to the tenth exemplary embodiment, since frequency of a shortcircuit decreases substantially and, delay of a common signal isdecreased, improvement of image quality and high yield are obtained.

Exemplary Embodiment 11

Next, an eleventh exemplary embodiment is described by referring to FIG.10. FIG. 10 is a plan view showing a configuration of a plurality ofpixels of an LCD device.

In the exemplary embodiment, common electrodes 1010, pixel electrodes1009 and a plurality of video signal wiring lines 1004 bend to form amulti-domain structure. In accordance with the structure, a direction ofa first reverse-rotation preventing structure 1015A is changed from adirection of a single domain.

According to the eleventh exemplary embodiment, frequency of a shortcircuit decreases substantially and a reverse-rotation of LC moleculesis prevented in whole display areas. A sufficient storage capacitance isformed. In a display device of the exemplary embodiment, since ablack-level luminance does not increase, high contrast is obtained. In adisplay device of the exemplary embodiment, even when viewing a screenin a oblique direction, color shift is suppressed by a multi-domainstructure.

Exemplary Embodiment 12

A twelfth exemplary embodiment is described by referring to FIG. 11. Twocommon signal wiring lines arranged in the upper part and the lower partof a pixel which are in a first storage capacity forming section and asecond storage capacity forming section are electrically connected by aconnection part arranged along a plurality of video signal wiring lines.

When the two common signal wiring lines 1102 of upper side and lowerside of the pixel are electrically connected to each other via aconnection part 1102B, delay of a common signal is decreased andin-plane distribution of luminance or a flicker level becomes uniform.The configuration contributes to high definition of a display. Theconfiguration is so effective for high definition of a display, whendevice is large and high definition is required. In the exemplaryembodiment, since the connection part 1102B is arranged along the sideof the plurality of video signal wiring lines, the leaked electric fieldfrom the plurality of video signal wiring lines to display areas issuppressed strongly and vertical cross talk is suppressed.

According to the twelfth exemplary embodiment, frequency of a shortcircuit decreases substantially and reverse-rotation is prevented inwhole display areas. In the exemplary embodiment, a sufficient storagecapacitance is formed. In a display device of the exemplary embodiment,because a black-level luminance does not increase, high contrast isobtained. Even when viewing a screen in an oblique direction, colorshift is suppressed by a multi-domain structure. Because a short circuitdecreases substantially and delay of a common signal decreases,improvement of image quality and high yield are obtained in a display ofthe exemplary embodiment.

Exemplary Embodiment 13

Next, a thirteenth exemplary embodiment is described by referring toFIG. 12. Common electrodes 1210 adjacent to pixel electrodes 1209 on aside that generates a fringe electric field in a first reverse-rotationpreventing structure 1215A include approximately crank shape inaccordance with the shape of the pixel electrode 1209. An enclosureeffect based on common electrodes is added to an effect of the fringeelectric field, and thereby a strong reverse-rotation prevention effectis obtained.

Thus, according to the thirteenth exemplary embodiment, frequency of ashort circuit decreases substantially and a reverse-rotation of LCmolecules is prevented in whole display areas, and efficiency for lightutilization increases.

Exemplary Embodiment 14

A fourteenth exemplary embodiment is described by referring to FIG. 12.A distance from edges of a concave portion 1214 formed by removing athird insulating film just below pixel electrodes to display areas isdefined.

When edges of the concave portion 1214 formed by removing the thirdinsulating film are close to display areas, light leak due to a stepoccurs to cause increase of black-level luminance. In the exemplaryembodiment, the distance from the edges of the concave portion 1214formed by removing the third insulating film to the display areas isdefined. Light leakage is effectively suppressed, when the distance islarge. If a distance of not less than 2 μm is kept, the light leakagedue to the step is intercepted with common signal wiring lines 1202, anda black-level luminance does not increase.

According to the fourteenth exemplary embodiment, frequency of a shortcircuit decreases substantially and reverse-rotation of LC molecules isprevented in whole display areas and a sufficient storage capacitance isformed. Since a black-level luminance does not increase, contrast of ascreen improves.

Exemplary Embodiment 15

Next, a fifteenth exemplary embodiment is described by referring to FIG.13. Two common signal wiring lines arranged in an upper part and a lowerpart of a pixel which are in a first storage capacity forming sectionand a second storage capacity forming section are electrically connectedby a connection part 1302B arranged along a plurality of video signalwiring lines.

When the two common signal wiring lines 1302 of upper side and lowerside of the pixel are electrically connected via a connection part1302B, delay of a common signal is decreased and in-plane distributionof luminance or a flicker level becomes uniform. The configurationcontributes to a display with high definition. The configuration is soeffective for high definition of a display when a device is large andhigh definition is required. In the exemplary embodiment, when theconnection part 1302B is arranged along the side of video signal wiringlines, the leaked electric field from the plurality of video signalwiring lines to display areas is suppressed strongly, and vertical crosstalk is suppressed.

According to the fifteenth exemplary embodiment, frequency of a shortcircuit decreases substantially, reverse-rotation of LC molecules isprevented in whole display areas, and efficiency for light utilizationincreases. In-plane distribution of luminance or a flicker level becomesuniform, vertical cross talk is suppressed, and image quality improves.

Exemplary Embodiment 16

Next, a sixteenth exemplary embodiment is described by referring to FIG.14. In the exemplary embodiment, common electrodes 1410, pixelelectrodes 1409 and a plurality of video signal wiring lines 1404 bendto form a multi-domain structure in a center of display areas. Inaccordance with the structure, a direction of a first reverse-rotationpreventing structure 1415A is different from a direction of the singledomain above mentioned in the thirteenth and the fourteenth exemplaryembodiment.

According to the sixteenth exemplary embodiment, frequency of a shortcircuit decreases substantially, reverse-rotation of LC molecules isprevented in whole display areas and efficiency for light utilizationincreases. In a display device of the exemplary embodiment, by amulti-domain structure, even when viewing a screen in an obliquedirection, color shift is suppressed.

Exemplary Embodiment 17

Next, a seventeenth exemplary embodiment is described by referring toFIG. 15. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected via a connection part arranged along a plurality of videosignal wiring lines.

When the two common signal wiring lines 1502 of upper side and lowerside of the pixel are connected to each other via a connection part1502B, delay of a common signal is decreased and in-plane distributionof luminance or a flicker level becomes uniform. The configurationcontributes to high definition of a display. The configuration is soeffective for high definition of a display, when a device is large andhigh definition is required. In the exemplary embodiment, when theconnection part 1502B is arranged along a side of the plurality of videosignal wiring lines, the leaked electric field from the plurality ofvideo signal wiring lines to display areas is suppressed strongly, andvertical cross talk is suppressed.

According to the seventeenth exemplary embodiment, frequency of a shortcircuit decreases substantially, the reverse-rotation of LC molecules isprevented in whole display areas, and efficiency for light utilizationincreases. Even when viewing a screen in an oblique direction, colorshift is suppressed by a multi-domain structure. In-plane distributionof luminance or a flicker level becomes uniform, vertical cross talk issuppressed, and image quality improves.

Exemplary Embodiment 18

Next, a eighteenth exemplary embodiment is described by referring toFIG. 16. In the exemplary embodiment, an angle of a direction in which afringe electric field which occurs in a neighborhood of a firstreverse-rotation preventing structure 1615A operates and an initialalignment direction of LC molecules in an LC layer are defined.

In FIG. 16, an angle between the direction in which the fringe electricfield operates and the initial alignment direction of the liquid crystallayer, that is, a rubbing direction is adjusted as θ. When the angle θis 45 degrees, the strongest running torque is applied to LC moleculesin the LC layer near the first reverse-rotation preventing structure1615A and reverse-rotation preventing effect becomes high. Accordingly,it is desirable that the angle θ is 45 degrees. However, due to a pitchof a plurality of pixels and a layout, when the angle θ cannot be set to45 degrees, a margin may be given to the value of θ. When the angle θ issettled in a predetermined range in which 45 degrees is central, enoughreverse-rotation preventing effect is obtained practically. When theangle θ is 30 to 60 degrees specifically, the enough reverse-rotationpreventing effect is obtained. When the angle θ is adjusted from 50degrees to 40 degrees, even if disturbance such as a finger push occurs,stable orientation can be kept. The angle θ is approximately in accordwith the angle between edges of a plurality of common signal wiringlines 1602 and edges of a part of pixel electrodes 1609 which inclinesin a direction different from a direction in the display areas thereof.

According to the eighteenth exemplary embodiment, by defining the angleθ which is formed by a direction in which a fringe electric fieldoperates and a initial alignment direction of LC molecules in an LClayer, a strong reverse-rotation preventing effect is obtained.

Exemplary Embodiment 19

Next, a nineteenth exemplary embodiment is described by referring toFIG. 16. A length of areas where a rotational direction of molecularaxes of liquid crystal molecules in a liquid crystal layer due to afringe electric field and a desired rotational direction of molecularaxes of LC molecules are identical is defined in the exemplaryembodiment.

The length above mentioned is described as d below. When the length d,from edges of common signal wiring lines, is adjusted to be longer thana thickness of an LC layer, a strong reverse-rotation preventing effectis obtained.

Thus, according to the nineteenth exemplary embodiment, since the angleθ and the length d above described are defined, the strongreverse-rotation preventing effect is obtained.

Exemplary Embodiment 20

Next, a twentieth exemplary embodiment is described by referring to FIG.16. Shapes of a plurality of common signal wiring lines are defined inthe embodiment.

Edges of a plurality of common signal wiring lines which face displayareas and determine boundaries of display areas of pixels are formed asstraight lines. In a related art, edges of common signal wiring linesinclude saw-like shapes, because reverse-rotation preventing structuresare formed thereon.

Thus, a transmitted light is scattered at wiring line edges.

According to the twentieth exemplary embodiment, when the edges of theplurality of common signal wiring lines which determine boundaries indisplay areas of pixels are formed to be simple linear shapes,scattering of transmitted light in the wiring line edges is suppressed.Since the plurality of common signal wiring lines of the exemplaryembodiment do not include saw-like shapes, scattering of transmissionlight is suppressed and approximately linearly-polarized-light stateespecially in a black display is not spoiled. Since a black-levelluminance does not increase, high contrast is obtained.

Exemplary Embodiment 21

Next, a twenty-first exemplary embodiment is described by referring toFIGS. 17 and 18. A display device of the exemplary embodiment isprovided with a different reverse-rotation preventing structure from thefirst reverse-rotation preventing structure above mentioned. FIG. 17 isa plan view showing a pixel configuration of an LCD device of theexemplary embodiment, and FIG. 18 is a drawing showing operation of LCmolecules in a reverse-rotation preventing structure of the exemplaryembodiment.

Specifically, electrode width at both ends of pixel electrodes 1709 ismade to be thick toward a side which a reverse-rotation electric fieldoccurs. Most of regions where electrode width at the ends of the pixelelectrode 1709 is made to be thick overlap a plurality of common signalwiring lines 1702 of a bottom layer.

FIG. 18 shows the reason why reverse-rotation is prevented by suchstructure, and a difference from the first reverse-rotation preventingstructure. In FIG. 18, near a region which reverse-rotation electricfield is generated, a width of pixel electrodes 1809 is thick, and aninterval between the pixel electrode 1809 and common electrodes 1810 isnarrow. Due to such configuration, a strong forward rotating electricfield occurs, and an operation of a reverse-rotation electric field issuppressed. In the first reverse-rotation preventing structure shown inFIG. 7A, edges of a plurality of common signal wiring lines 702intersect with part of pixel electrodes which incline in a directiondifferent from a direction thereof in display areas. A fringe electricfield for a forward rotation of LC molecules occurs between theplurality of common signal wiring lines 702 and edges of pixelelectrodes 709. Thus an influence of a reverse-rotating electric fieldis suppressed. In a reverse-rotation preventing structure shown in FIG.18, a strong forward rotating electric field is generated between thepixel electrode 1809 and the common electrodes 1810. Hereafter, thereverse-rotation preventing structure shown in FIG. 18 is called asecond reverse-rotation preventing structure.

According to the twenty-first exemplary embodiment, frequency of a shortcircuit decreases substantially, an effect of preventingreverse-rotation of LC molecules in whole display areas increases, andefficiency for light utilization increases. Marks of a finger push donot remain on a screen of an LC panel.

Exemplary Embodiment 22

Next, a twenty-second exemplary embodiment is described by referring toFIG. 17. A distance from edges of a concave portion formed by removing athird insulating layer just below pixel electrodes to display areas isdefined.

When edges of the concave portion 1714 formed by removing the thirdinsulating film are close to display areas, light leak caused due to astep occurs to cause increase of black-level luminance. Accordingly, inthe exemplary embodiment, the distance from the edges of the concaveportion 1714 formed by removing the third insulating film to the displayareas is defined. Light leakage is well suppressed, when the distance islarge. If the distance of not less than 2 μm is kept, the light leakagedue to the step is intercepted with common signal wiring lines 1702, anda black-level luminance does not increase.

According to the twenty-second exemplary embodiment, frequency of ashort circuit decreases substantially, reverse-rotation of LC moleculesis prevented in whole display areas, and a sufficient storagecapacitance is formed. Since a black-level luminance does not increase,a contrast improves.

Exemplary Embodiment 23

Next, a twenty-third exemplary embodiment is described by referring toFIG. 19. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected by a connection part 1902B arranged along a plurality of videosignal wiring lines.

By connecting the two common signal wiring lines 1902 of upper side andlower side of the pixel with a connection part 1902B, delay of a commonsignal is decreased and in-plane distribution of luminance or a flickerlevel becomes uniform. The configuration contributes to high definitionof a display. The configuration is so effective for high definition of adisplay when a device is large and high definition is required. In theexemplary embodiment, when the connection part 1902B is arranged along aside of the plurality of video signal wiring lines, a leakage electricfield from the plurality of video signal wiring lines to display areasis suppressed strongly, and vertical cross talk is suppressed.

According to the twenty-third exemplary embodiment, frequency of a shortcircuit decreases substantially, an effect of preventingreverse-rotation of LC molecules in whole display areas increases, andefficiency for light utilization increases. Marks of a finger push donot remain on a screen of an LC panel. In-plane distribution ofluminance or a flicker level becomes uniform, vertical cross talk issuppressed, an image quality improves.

Exemplary Embodiment 24

Next, a twenty-fourth exemplary embodiment is described by referring toFIG. 20. Common electrodes 2010, pixel electrodes 2009 and a pluralityof video signal wiring lines 2004 bend to form a multi-domain structurein a center of display areas.

In accordance with the structure, a direction of a secondreverse-rotation preventing structure 2015B is changed from a directionof a single domain described in the twenty-first and the twenty-secondexemplary embodiment.

According to the twenty-fourth exemplary embodiment, frequency of ashort circuit decreases substantially, an effect of preventingreverse-rotation of LC molecules in whole display areas increases, andefficiency for light utilization increases. Marks of a finger push donot remain on a screen of an LC panel. Even if viewing a screen in anoblique direction, color shift is suppressed by the multi-domainstructure.

Exemplary Embodiment 25

Next, a twenty-fifth exemplary embodiment is described by referring toFIG. 21. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected by a connection part arranged along a plurality of videosignal wiring lines.

By connecting the two common signal wiring lines 2102 of an upper sideand a lower side of a pixel with a connection part 2102B, delay of acommon signal is decreased and in-plane distribution of luminance or aflicker level becomes uniform. The configuration contributes to highdefinition of a display and is so effective for high definition of adisplay when a device is large and high definition is required. In theexemplary embodiment, when the connection part 2102B is arranged along aside of a plurality of video signal wiring lines, a leakage electricfield from the plurality of video signal wiring lines to display areasis suppressed strongly, and vertical cross talk is suppressed.

According to the twenty-fifth exemplary embodiment, frequency of a shortcircuit decreases substantially, an effect of preventingreverse-rotation of LC molecules in whole display areas increases, andefficiency for light utilization increases. Marks of a finger push donot remain on a screen of an LC panel. Even if viewing a screen in anoblique direction, a color shift is suppressed by a multi-domainstructure. In-plane distribution of luminance or a flicker level becomesuniform and vertical cross talk is suppressed, and image qualityimproves.

Exemplary Embodiment 26

Next, a twenty-sixth exemplary embodiment is described by referring toFIGS. 22 and 23. In a second reverse-rotation preventing structure2215B, common electrodes 2210 adjacent to pixel electrodes 2209 havingwide edges becomes a shape of an approximately crank type in accordancewith the shapes of pixel electrodes 2209. Then an effect of suppressinga reverse-rotation electric field becomes still higher in the exemplaryembodiment.

A reason for the effect is described by referring to FIG. 23. In aregion where corner parts of electrode edges are close to each other, astrong forward rotating electric field occurs. The electric fieldapplies a strong rotating torque in an initial alignment direction of LCmolecules. Specifically, a initial alignment direction of the LCmolecules and a direction where the forward rotating electric fieldoperates form around 45 degrees. An effect for suppressing areverse-rotation electric field becomes still higher in the exemplaryembodiment.

According to the twenty-sixth exemplary embodiment, frequency of a shortcircuit decreases substantially, an effect for preventing thereverse-rotation of the LC molecules in whole display areas increases,and efficiency for light utilization increases. Marks of a finger pushdo not remain on a screen of an LC panel.

Exemplary Embodiment 27

Next, a twenty-seventh exemplary embodiment is described by referring toFIG. 22. A distance from edges of a concave portion formed by removing athird insulating layer just below pixel electrodes to display areas isdefined in the exemplary embodiment.

The exemplary embodiment is described in detail. When edges of theconcave portion 2214 formed by removing the third insulating film areclose to display areas, light leak caused by a step occurs to causeincrease of black-level luminance. Accordingly, in the exemplaryembodiment, the distance from the edges of the concave portion 2214formed by removing the third insulating film to the display areas isdefined. Light leakage is well suppressed, when the distance is large.If a distance of not less than 2 μm is kept, the light leakage due to astep is intercepted with a plurality of common signal wiring lines 1702,and a black-level luminance does not increase.

Thus, according to the twenty-seventh exemplary embodiment, frequency ofa short circuit decreases substantially, reverse-rotation of LCmolecules is prevented in whole display areas, and a sufficient storagecapacitance is formed. Since black-level luminance does not increase,contrast improves.

Exemplary Embodiment 28

Next, a twenty-eighth exemplary embodiment is described by referring toFIG. 24. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected via a connection part arranged along a plurality of videosignal wiring lines.

When the two common signal wiring lines 2402 of an upper side and alower side of the pixel with a connection part 2402B are connected,delay of a common signal is decreased and in-plane distribution ofluminance or a flicker level becomes uniform. The configurationcontributes to high definition of a display and is so effective for highdefinition of a display when a device is large and high definition isrequired. In the exemplary embodiment, when the connection part 2402B isarranged along a side of the plurality of video signal wiring lines, theleakage electric field from the plurality of video signal wiring linesto display areas is suppressed strongly, and vertical cross talk issuppressed.

According to the twenty-eighth exemplary embodiment, frequency of eshort circuit decreases substantially, reverse-rotation of LC moleculesis prevented in whole display areas, and efficiency for lightutilization increases. Marks of a finger push do not remain on a screenof an LC panel. In-plane distribution of luminance or a flicker levelbecomes uniform, vertical cross talk is suppressed, and image qualityimproves.

Exemplary Embodiment 29

Next, a twenty-ninth exemplary embodiment is described by referring toFIG. 25. Common electrodes 2510, pixel electrodes 2509 and a pluralityof video signal wiring lines 2504 bend to form a multi-domain structurein a center of display areas. In accordance with the structure, adirection of a second reverse-rotation preventing structure 2515B ischanged from a direction in the single domain described in thetwenty-sixth and the twenty-seventh exemplary embodiment.

According to the twenty-ninth exemplary embodiment, frequency of a shortcircuit decreases substantially, reverse-rotation of LC molecules isprevented in whole display areas, and efficiency for light utilizationincreases. Marks of a finger push do not remain on a screen of an LCpanel. Even if viewing a screen in an oblique direction, a color shiftis suppressed by a multi-domain structure.

Exemplary Embodiment 30

Next, a thirtieth exemplary embodiment is described by referring to FIG.26. Two common signal wiring lines arranged in an upper part and a lowerpart of a pixel which are in a first storage capacity forming sectionand a second storage capacity forming section are electrically connectedvia a connection part arranged along a plurality of video signal wiringlines.

When the two common signal wiring lines 2602 of an upper side and alower side of the pixel with a connection part 2602B are connected,delay of a common signal is decreased and in-plane distribution ofluminance or a flicker level becomes uniform. The configurationcontributes to high definition of a display and is so effective for highdefinition of a display when a device is large and high definition isrequired. In the exemplary embodiment, when the connection part 2602B isarranged along a side of the plurality of video signal wiring lines, aleakage electric field from the plurality of video signal wiring linesto display areas is suppressed strongly, and vertical cross talk issuppressed.

Thus, according to the twenty-fifth exemplary embodiment, frequency of ashort circuit decreases substantially, reverse-rotation of LC moleculesis prevented in whole display areas, and efficiency for lightutilization increases. Marks of a finger push do not remain on a screenof an LC panel. Even if viewing a screen in an oblique direction, acolor shift is suppressed by a multi-domain structure. In-planedistribution of luminance or a flicker level becomes uniform, verticalcross talk is suppressed, and image quality improves.

Exemplary Embodiment 31

Next, a thirty-first exemplary embodiment is described by referring toFIG. 27. A first reverse-rotation preventing structure 2715A is used inone side (i.e. lower side) of a pixel and a second reverse-rotationpreventing structure 2715B is used in the other side (i.e. upper side)of a pixel. Such combination of such reverse-rotation preventingstructures may be upside down, and may be freely set according to adesign condition.

According to the thirty-first exemplary embodiment, frequency of a shortcircuit decreases substantially, reverse-rotation of LC molecules isprevented in whole display areas, and efficiency for light utilizationincreases. Marks of a finger push do not remain on a screen of an LCpanel.

Exemplary Embodiment 32

Next, a thirty-second exemplary embodiment is described by referring toFIG. 27. A distance from edges of a concave portion formed by removing athird insulating layer just below pixel electrodes to display areas isdefined.

When edges of the concave portion 2714 formed by removing the thirdinsulating film are close to display areas, light leak caused by a stepoccurs to cause increase of black-level luminance. Accordingly, in theexemplary embodiment, the distance from the edges of the concave portion2714 formed by removing the third insulating film to the display areasis defined. Light leakage is well suppressed, when the distance islarge. If the distance of not less than 2 μm is kept, the light leakagedue to the step is intercepted with a plurality of common signal wiringlines 1702, and a black-level luminance does not increase.

According to the thirty-second exemplary embodiment, frequency of ashort circuit decreases substantially and reverse-rotation of LCmolecules is prevented in whole display areas, and a sufficient storagecapacitance is formed. Since a black-level luminance does not increase,a contrast improves.

Exemplary Embodiment 33

Next, a thirty-third exemplary embodiment is described by referring toFIG. 28. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected via a connection part arranged along a plurality of videosignal wiring lines.

When the two common signal wiring lines 2802 of an upper side and alower side of the pixel are connected by a connection part 2802B, delayof a common signal is decreased and in-plane distribution of luminanceor a flicker level becomes uniform. The configuration contributes tohigh definition of a display and is so effective for high definition ofa display when a device is large and high definition is required. In theexemplary embodiment, when the connection part 2802B is arranged along aside of the plurality of video signal wiring lines, the leakage electricfield from the plurality of video signal wiring lines to display areasis suppressed strongly, and vertical cross talk is suppressed.

According to the thirty-third exemplary embodiment, frequency of a shortcircuit decreases substantially, reverse-rotation of LC molecules isprevented in whole display areas increases, and efficiency for lightutilization increases. Marks of a finger push do not remain on a screenof an LC panel. In-plane distribution of luminance or a flicker levelbecomes uniform, vertical cross talk is suppressed, and image qualityimproves.

Exemplary Embodiment 34

Next, a thirty-fourth exemplary embodiment is described by referring toFIG. 29. Common electrodes 2910, pixel electrodes 2909 and a pluralityof video signal wiring lines 2904 bend to form a multi-domain structurein a center of display areas. In accordance with the structure, adirection of a second reverse-rotation preventing structure 2915B ischanged from a direction of the single domain described in thetwenty-third exemplary embodiment.

According to the thirty-fourth exemplary embodiment, frequency of ashort circuit decreases substantially and reverse-rotation of LCmolecules is prevented in whole display areas and efficiency for lightutilization increases. Marks of a finger push do not remain on a screenof an LC panel. Even if viewing a screen in an oblique direction, acolor shift is suppressed by a multi-domain structure.

Exemplary Embodiment 35

Next, a thirty-fifth exemplary embodiment is described by referring toFIG. 30. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected by a connection part 1902B arranged along a plurality of videosignal wiring lines.

When the two common signal wiring lines 3002 of an upper side and alower side of the pixel are connected by a connection part 3002B, delayof a common signal is decreased and in-plane distribution of luminanceor a flicker level becomes uniform. The configuration contributes tohigh definition of a display, and is so effective for high definition ofa display when a device is large and high definition is required. In theexemplary embodiment, when the connection part 3002B is arranged along aside of the plurality of video signal wiring lines, a leakage electricfield from the plurality of video signal wiring lines to display areasis suppressed strongly, and vertical cross talk is suppressed.

According to the thirty-fifth exemplary embodiment, frequency of a shortcircuit decreases substantially, an effect of preventingreverse-rotation of LC molecules in whole display areas increases, andefficiency for light utilization increases. Marks of a finger push donot remain on a screen of an LC panel. In a display device of theexemplary embodiment, due to a multi-domain structure, even if viewing ascreen in an oblique direction, color shift is suppressed. In-planedistribution of luminance or a flicker level becomes uniform, verticalcross talk is suppressed, and image quality improves.

Exemplary Embodiment 36

Next, a thirty-sixth exemplary embodiment is described by referring toFIG. 31. In a second reverse-rotation preventing structure 3115B, commonelectrodes 3110 adjacent to pixel electrodes 3109 does not includesshapes thoroughly along with shapes of pixel electrodes 3109, butincludes shapes in which near a tip thereof is slanted. Even whenchanging shapes, an effect for suppressing a reverse-rotation electricfield remains unchanged, and shapes of the common electrodes 3110 may befreely formed according to a design condition. The shapes of the commonelectrodes 3110 according to this exemplary embodiment are effective,when a column width is narrow and common electrodes of right-angledcrank shapes cannot be made easily.

According to the thirty-sixth exemplary embodiment, frequency: of ashort circuit decreases substantially, reverse-rotation of LC moleculesis prevented in whole display areas, and efficiency for lightutilization increases. Marks of a finger push do not remain on a screenof an LC panel.

Exemplary Embodiment 37

Next, a thirty-seventh exemplary embodiment is described by referring toFIG. 31. A distance from edges of a concave portion formed by removing athird insulating layer just below pixel electrodes to display areas isdefined.

When edges of the concave portion 3114 formed by removing the thirdinsulating film are close to display areas, light leak caused by a stepoccurs to cause increase of black-level luminance. Accordingly, in theexemplary embodiment, the distance from the edges of the concave portion3114 formed by removing the third insulating film to the display areasis defined. Light leakage is well suppressed, when the distance islarge. If the distance of not less than 2□m is kept, the light leakagedue to the step is intercepted with common signal wiring lines 1702, anda black-level luminance does not increase.

According to the thirty-seventh exemplary embodiment, frequency of ashort circuit decreases substantially and reverse-rotation of LCmolecules is prevented in whole display areas, and a sufficient storagecapacitance is formed. Since a black-level luminance does not increase,a contrast improves.

Exemplary Embodiment 38

Next, a thirty-eighth exemplary embodiment is described by referring toFIG. 32. Two common signal wiring lines arranged in an upper part and alower part of a pixel which are in a first storage capacity formingsection and a second storage capacity forming section are electricallyconnected by a connection part 1902B arranged along a plurality of videosignal wiring lines.

When the two common signal wiring lines 3202 of an upper side and alower side of the pixel are connected by the connection part 3202B,delay of a common signal is decreased and in-plane distribution ofluminance or a flicker level becomes uniform. The configurationcontributes to high definition of a display and is so effective for highdefinition of a display when a device is large and high definition isrequired. In the exemplary embodiment, when the connection part 3202B isarranged along a side of the plurality of video signal wiring lines, aleakage electric field from the plurality of video signal wiring linesto display areas is suppressed strongly, and vertical cross talk issuppressed.

According to the thirty-eighth exemplary embodiment, frequency of ashort circuit decreases substantially and reverse-rotation of LCmolecules is prevented in whole display areas, and efficiency for lightutilization increases. Marks of a finger push do not remain on a screenof an LC panel. In-plane distribution of luminance or a flicker levelbecomes uniform, vertical cross talk is suppressed, and image qualityimproves.

Exemplary Embodiment 39

Next, a thirty-ninth exemplary embodiment is described by referring toFIG. 33. Common electrodes 3310, pixel electrodes 3309 and a pluralityof video signal wiring lines 3304 bend to form a multi-domain structurein a center of display areas. In accordance with the structure, adirection of a second reverse-rotation preventing structure 3315B ischanged from a direction of a single domain described in thethirty-sixth and the thirty-seventh exemplary embodiment.

According to the thirty-ninth exemplary embodiment, frequency of a shortcircuit decreases substantially and reverse-rotation of LC molecules isprevented in whole display areas, and efficiency for light utilizationincreases. Marks of a finger push do not remain on a screen of an LCpanel. Even if viewing a screen in an oblique direction, a color shiftis suppressed by the multi-domain structure.

Exemplary Embodiment 40

Next, a fortieth exemplary embodiment is described by referring to FIG.34. Two common signal wiring lines arranged in an upper part and a lowerpart of a pixel which are in a first storage capacity forming sectionand a second storage capacity forming section are electrically connectedby a connection part 1902B arranged along a plurality of video signalwiring lines.

When the two common signal wiring lines 3402 of an upper side and alower side of the pixel are connected by the connection part 3402B,delay of a common signal is decreased and in-plane distribution ofluminance or a flicker level becomes uniform. The configurationcontributes to high definition of a display, and is so effective forhigh definition of a display when a device is large and high definitionis required. In the exemplary embodiment, the connection part 3402B isarranged along a side of the plurality of video signal wiring lines, aleakage electric field from the plurality of video signal wiring linesto display areas is suppressed strongly, and vertical cross talk issuppressed.

According to the fortieth exemplary embodiment, frequency of a shortcircuit decreases substantially and reverse-rotation of LC molecules isprevented in whole display areas, and efficiency for light utilizationincreases. Marks of a finger push do not remain on a screen of an LCpanel. Even if viewing a screen in an oblique direction, color shift issuppressed by a multi-domain structure. In-plane distribution ofluminance or a flicker level becomes uniform, vertical cross talk issuppressed, and image quality improves.

Exemplary Embodiment 41

Next, a forty-first exemplary embodiment is described by referring toFIGS. 18 and 23. A positional relationship between edges of a regionhaving a wide width in both ends of pixel electrodes and edges of aplurality of common signal wiring lines are defined.

As shown in FIGS. 18 and 23, in order to suppress a reverse-rotationelectric field, it is desirable that edges of the wide width region ofthe ends of the pixel electrode project, by 1 μm to 4 μm, from the edgesof the plurality of common signal wiring lines. However, even when theedges of the wide width region of the ends of the pixel electrode goback, by around 1 μm, from the edges of the plurality of common signalwiring lines, reverse-rotation of LC molecules is prevented. Therefore,the edges of the wide width region of the ends of the pixel electrodemay be formed, in a range from 1 μm inside to 4 μm outside, with respectto the edges of the plurality of common signal wiring lines.

According to the forty-first exemplary embodiment, a reverse-rotationpreventing structure for LC molecules in whole display areas includes alarge process margin to easily align a mask or the like.

Exemplary Embodiment 42

Next, a forty-second exemplary embodiment is described by referring toFIGS. 18 and 23. Shapes of a plurality of common signal wiring lines aredefined in the embodiment.

Edges of a plurality of common signal wiring lines which face displayareas and define boundaries of display areas of pixels include straightline shapes. In a related art, edges of common signal wiring linesinclude saw-like shapes since a reverse-rotation preventing structure isformed thereat. Therefore, a transmitting light is scattered in theedges of the wiring lines.

According to the forty-second exemplary embodiment, since edges of theplurality of common signal wiring lines which define boundaries indisplay areas of pixels are formed to be simple linear shapes,scattering of transmitting light in the wiring line edges is suppressed.Since the scattering of a transmitting light is suppressed, alinearly-polarized-light state in a black display is not spoiled.Further since a black-level luminance does not increase, high contrastis obtained.

In each above-mentioned exemplary embodiment, a TFT is described as aswitching element. In the present invention, however, other elements,such as a thin film diode (TFD), can also be used as a switchingelement. A configuration of a substrate facing a TFT substrate, aconfiguration of an optical member arranged on the outside of the liquidcrystal panel which includes a TFT substrate, a counter substrate, andan LC layer, and a configuration of back light for illuminating an LCpanel, etc. are not limited to the above-mentioned and can employ anyavailable technology.

The first and second reverse-rotation preventing structures and thestructure in which source electrodes are reduced are combined in eachabove-mentioned exemplary embodiment. However such reverse-rotationpreventing structures are not necessarily applied only to the structurein which source electrodes are reduced. Such reverse-rotation preventingstructures can be applied to a device which includes a plurality ofcommon signal wiring lines and common electrodes and pixel electrodesthereon, and can prevent disinclination of ends of a plurality of pixelsto realize high contrast.

The above-mentioned exemplary embodiments describe examples in which twoinsulating layers are disposed on a plurality of video signal wiringlines, and pixel electrodes and common electrodes thereon. However, inabove mentioned structure, one insulating layer or more than oneinsulating layers are available.

THE AVAILABILITY ON THE INDUSTRY

The present invention is available to an active matrix type LCD deviceof a lateral electric field type, and arbitrary instruments which usethis LCD device as a display device.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto these embodiments. It will be understood by those of ordinary skillin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the claims.

Further, it is the inventor's intention to retain all equivalents of theclaimed invention even if the claims are amended during prosecution.

1. An active matrix liquid crystal display device, comprising: a first substrate including: a scan signal wiring line; a common signal wiring line parallel to the scan signal wiring line; a video signal wiring line intersecting the scan signal wiring line and the common signal wiring line; and a pixel, which is disposed in a first region surrounded with the scan signal wiring line and the video signal wiring line, and includes: a thin film transistor; a source electrode of the thin film transistor formed in the same layer as the video signal wiring line; a pixel electrode connected to the source electrode; and a common electrode connected to the common signal wiring line, a third region in the edge of the display area, in which the molecular axis of the liquid crystal molecule in the liquid crystal layer rotates in a different direction from the first direction under an electric field applied between an edge of the pixel electrode in the display area and an edge of the common signal wiring line on a side of the display area; a fourth region on the common signal wiring line, which is close to the third region, a second substrate facing the first substrate; and a liquid crystal layer sandwiched by the first substrate and the second substrate, wherein a molecular axis of liquid crystal can be rotated in a plane parallel to the first substrate by the electric field between the pixel electrode and the common electrode, the pixel electrode overlaps with the common signal wiring line at an end of the pixel electrode, and in a region where the pixel electrode overlaps with the common signal wiring line, at the side of the pixel electrode where the electric field between the common signal wiring line and the pixel electrode rotates the molecular axis of liquid crystal in the direction, which is opposite to the direction to which the electric field between the pixel electrode and the common electrode in the adjacent display area rotates the molecular axis of liquid crystal, a width of the pixel electrode is increased, so as to face the common electrode with a narrower electrode spacing, and the pixel electrode edge, which is along the boundary between the pixel electrode with increased width and the display area, is parallel to the common signal wiring line edge which is along the boundary with the display area, and the molecular axis of the liquid crystal molecule in the liquid layer rotates in the first direction under a fringe electric field, which occurs in a vicinity of an edge of the pixel electrode in the fourth region, the pixel electrode overlapping with the common signal wiring line in the fourth region.
 2. The active matrix liquid crystal display device according to claim 1, wherein the edge of the pixel electrode in the region having the increased width at the end of the pixel electrode, the edge facing the display area, is positioned, by 1 μm, inside the common signal wiring line to, by 4 μm, outside the common signal wiring line.
 3. The active matrix liquid crystal display device according to claim 1, wherein an edge of the common electrode, adjacent to the region having the increased width at the end of the pixel electrode, is bent in accordance with a shape of the pixel electrode.
 4. The active matrix liquid crystal display device according to claim 3, wherein an edge of the pixel electrode and the common electrode having an edge which is bent in accordance with the edge of the pixel electrode are bent in a crank shape in the end of the pixel electrode.
 5. The active matrix liquid crystal display device according to claim 1, wherein a part which defines a boundary of the display area of the pixel in an edge of the common signal wiring line includes a straight line shape, the edge facing the display area.
 6. The active matrix liquid crystal display device according to claim 1, wherein an edge of the pixel electrode of the part having the increased electrode width, is parallel to the edge of the facing common electrode.
 7. An active matrix liquid crystal display device, comprising: a first substrate including: a scan signal wiring line; a common signal wiring line disposed along the scan signal wiring line; a video signal wiring line intersecting the scan signal wiring line and the common signal wiring line; and a pixel, which is disposed in a first region surrounded with the scan signal wiring line and the video signal wiring line, and includes: a thin film transistor; a source electrode of the thin film transistor formed in a layer in which the video signal wiring line is disposed; a pixel electrode connected to the source electrode; a common electrode connected to the common signal wiring line, the source electrode including a first part overlapping with the scan signal wiring line and a second part connecting with the pixel electrode, the second part being positioned in a central part between the video signal wiring lines in both sides of the pixel; and a first storage capacitance forming region, which is formed in an area, which does not include the liquid crystal layer, and where the source electrode or the pixel electrode overlaps with the common electrode or the common signal wiring line; a second substrate facing the first substrate; and a liquid crystal layer sandwiched by the first substrate and the second substrate, a molecular axis of a liquid crystal molecule in the liquid crystal layer rotating in a first direction in a plane approximately parallel to the first substrate under an electric field, which is approximately parallel to the first substrate and is applied between the pixel electrode and the common electrode, wherein the scan signal wiring line and the common signal wiring line are formed in a layer, which is located under the video signal wiring line via a first insulating layer, the pixel electrode and the common electrode are formed in a layer, which is located above the video signal wiring line via a second insulating layer, the first storage capacitance forming region includes: a first storage capacitance formed by overlapping the pixel electrode and the common signal wiring line; and a second storage capacitance formed by overlapping the source electrode and the common signal wiring line, and the first storage capacitance in the first storage capacitance forming region is more than a half of the second storage capacitance.
 8. The active matrix liquid crystal display device according to claim 7, wherein the first storage capacitance forming region includes a second region where a part of an insulating film is removed, the insulating film being formed in a layer which is located above the video signal wiring line and under the pixel electrode.
 9. The active matrix liquid crystal display device according to claim 7, wherein the insulating film includes two or more than two layers, each including a different material, and at least one of the layers is removed in the second region.
 10. The active matrix liquid crystal display device according to claim 9, wherein the two or more than two layers include an inorganic layer and an organic layer.
 11. The active matrix liquid crystal display device according to claim 8, wherein a distance between an edge of the second region and the display area is not less than 2 μm.
 12. The active matrix liquid crystal display device according to claim 7, further comprising: a second storage capacitance forming region which is located, in the first region, along the scan signal wiring line, wherein the first storage capacitance forming region is formed in a side near the thin film transistor, and the second storage capacitance forming region is formed in a side far from the thin film transistor and includes a third storage capacitance which is formed by overlapping the common signal wiring line with the pixel electrode.
 13. The active matrix liquid crystal display device according to claim 12, wherein a first common signal wiring line including the first storage capacitance forming region and a second common signal wiring line including the second storage capacitance forming region are electrically connected in the first region.
 14. The active matrix liquid crystal display device according to claim 13, wherein a part which electrically connects the first common signal wiring line and the second common signal wiring line is arranged along the video signal wiring line.
 15. The active matrix liquid crystal display device according to claim 1, wherein an edge of the common electrode adjacent to a side of the pixel electrode, near an edge thereof, in which the fringe electric field occurs is bent in accordance with a shape of the pixel electrode.
 16. The active matrix liquid crystal display device according to claim 15, wherein the bent shape of the common electrode includes a crank shape.
 17. The active matrix liquid crystal display device according to claim 1, wherein an angle between a direction where the fringe electric field operates and an initial alignment direction of the liquid crystal layer is 30 degrees to 60 degrees.
 18. The active matrix liquid crystal display device according to claim 1, wherein an angle between a direction where the fringe electric field operates and an initial alignment direction of the liquid crystal layer is 40 degrees to 50 degrees.
 19. The active matrix liquid crystal display device according to claim 1, wherein an angle between a direction where the fringe electric field operates and an initial alignment direction of the liquid crystal layer is 45 degrees.
 20. The active matrix liquid crystal display device according to claim 1, wherein a region, in which the molecular axis of the liquid crystal molecule in the liquid crystal layer rotates in the first rotational direction under the fringe electric field includes a region, which is separated from an edge of the common signal wiring line at a distance more than a thickness of the liquid crystal layer.
 21. The active matrix liquid crystal display device according to claim 1, wherein a part which defines a boundary of the display area of the pixel in an edge of the common signal wiring line includes a straight line shape, the edge facing the display area.
 22. A pixel disposed in an active matrix liquid crystal display device in a region surrounded with a scan signal wiring line and a video signal wiring line, comprising: a thin film transistor; a source electrode of the thin film transistor formed in a layer in which the video signal wiring line is disposed; a pixel electrode connected to the source electrode; and a common electrode connected to a common signal wiring line disposed along the scan signal wiring line, the source electrode including a first part overlapping the scan signal wiring line and a second part connecting with the pixel electrode, the second part being positioned around a central part between the video signal wiring lines, a molecular axis of a liquid crystal molecule in a liquid crystal layer rotating under an electric field, which is applied between the pixel electrode and the common electrode, wherein in a third region in an edge of a display area the molecular axis of the liquid crystal molecule in the liquid crystal layer rotates in a different direction from the first direction under an electric field applied between an edge of the pixel electrode in the display area and an edge of the common signal wiring line on a side of the display area, a fourth region on the common signal wiring line is disposed close to the third region, and the molecular axis of the liquid crystal molecule in the liquid layer rotates in the first direction under a fringe electric field, which occurs in a vicinity of an edge of the pixel electrode in the fourth region, the pixel electrode overlapping with the common signal wiring line in the fourth region. 